Hard to say. There is a lot of difference between what Japanese society in general thinks is okay for an 11-year-old and what American society in general thinks is okay. (And of course it also depends on your own beliefs, and the interest of the kid.) Lots of it is too violent, or too sexual. Also slow “slice of life” he might be bored by. Or relationship/dating drama/humor he might not appreciate. Probably most of the stuff enjoyable to an 11-year-old is the sort of action/fighting shows that I don’t watch so can’t comment on.
But from ones mentioned in this thread
Delicious in Dungeon is probably a good choice. Lots of action but nothing too graphic or terrifying for a kid. And very little fan service except for of a middle-aged male dwarf.
Beastars is very well-done. Like Zootopia, but really leans into some of the problems of carnivore species attempting to live peacefully with herbivore species. (Devourings happen.) Some PG-13, CW-level sexuality.
Speaking of anthropomorphic animals, Oddtaxi I mentioned earlier is good, but might be boring for an 11-year-old because it is more adult drama themed.